(-3-y)²

To expand the expression \((-3-y)^2\), you square each term inside the parentheses and apply the distributive property (FOIL method for binomials) to account for the cross terms. Here's the step-by-step expansion:

\[ (-3 - y)^2 = (-3 - y) \cdot (-3 - y) \]

Applying the FOIL method, you multiply each term in the first binomial by each term in the second binomial:

1. Multiply the first terms: \((-3) \cdot (-3) = 9\)
2. Multiply the outer terms: \((-3) \cdot (-y) = 3y\)
3. Multiply the inner terms: \((-y) \cdot (-3) = 3y\)
4. Multiply the last terms: \((-y) \cdot (-y) = y^2\)

Add all these results together:

\[ 9 + 3y + 3y + y^2 \]

Combine like terms (the 3y terms):

\[ 9 + 6y + y^2 \]

It's common to write polynomial expressions in descending order of power, so the expanded form of \((-3 - y)^2\) in standard form is:

\[ y^2 + 6y + 9 \]